Closing in on humanity’s oldest mystery
IT'S an image imprinted on our brains: the steady march of evolution from chimp to human. But it's not quite right.
Monkeys don't belong on the tree. They have tails.
Chimps, which don't, are with Bonobos our closest living relatives. And, as such, both should be standing alongside us in the march of life.
Stretching out behind should be a gradually converging branch of earlier variations.
Ultimately, between six and eight million years ago, the branches almost certainly converge on one common ancestor.
We know almost nothing about what that was.
No fossils have yet been found.
However, we do have many hominid fossils from the branches of the evolutionary tree extending both towards and from that point.
So, scientists in California have begun training an artificial intelligence to identify the defining aspects of human and ape ancestors. How our shared physiology converges back in time could offer clues about our original forebear.
TAKING A BITE OUT OF HISTORY
The researchers used machine learning to teach an artificial intelligence to identify and classify fossilised hominid teeth dating from 25 million years ago. It then sifted through these to find patterns of development.
Our common ancestor almost certainly had gorilla-like teeth.
Now, it's not a lot. And it certainly doesn't say our ancestor was a gorilla.
But what it does do is add some shape and substance to this nebulous period of our human origins.
And it's not what science expected.
The chimpanzee had been the 'guesstimate' template upon which our original ancestor's shape and form had been based. Now researchers are going to have to reinterpret what they know.
"For decades, palaeontologists have used the chimpanzee as a model for the chimpanzee-human last common ancestor (LCA) because they are our closest living primate relative," the study reads. "However, relative dental proportions of Miocene hominoids are more similar to extant gorillas and follow a strong trajectory through evolutionary time."
THE MONKEY'S UNCLE
"The fossils we have actually look quite different from anything living today, and likely the LCA looked quite different too - but they looked more like gorillas," biological anthropologist Dr Tesla Monson told Inverse.
"While we aren't able to say exactly what the teeth of the LCA looked like until we find the fossils - just one reason why palaeontological excavations are so important - we can generate some hypothesis based on what other apes looked like."
The difference between the modern DNA of humans and chimpanzees is just 1.2 per cent. Between humans and gorillas, it's about 1.6 per cent.
So there is plenty of research still to be done to find out what our oldest common ancestor looked like - in terms of size, build and shape.
But AI is already on the job.
"Machine learning is a formidable tool for pattern recognition in large datasets. We developed and expanded on these methods, applying machine learning pattern recognition to a problem in palaeoanthropology and evolution," the study reads.